Until recently pulses of neutrons could be obtained from plasma generators like those developed in research on controlled thermonuclear devices, from pulsed fission reaction, and from laser created plasma where a high energy pulse of laser radiation is used to heat a target of solid deuterium. It is now also feasible to use pulsed laser radiation to heat the plasma of generators like the coaxial plasma gun to obtain intense pulses in excess of 10.sup.11 neutrons per burst such as disclosed in U.S. Pat. No. 3,766,004. However, it should be pointed out that any method which heats the plasma during a very short time (nanoseconds) produces the same results, and the most intense pulses of neutrons which are obtained from the fission reactors are very expensive and produce radioactive waste.
Absorption of some of the energy of an electron beam by a plasma would increase its temperature and thereby increase the number of neutrons produced by the plasma. When the plasma temperature is increased the neutron production goes up by the ratio of .sigma.v at the final temperature to .sigma.v at the initial temperature. Here .sigma.v is the product of the relative velocity v and the reaction cross section .sigma. averaged over the velocity distribution of the nuclei. For the conditions produced in the plasma gun, doubling the temperature can cause an order of magnitude increase in the neutron yield.
Therefore, it is an object of this invention to provide a neutron generator in which the energies from an electron source and a plasma generator are combined to produce neutrons.
Another object of this invention is to provide a neutron generator in which electrons from an electron beam source are guided and focused onto a hot plasma produced by a plasma generator.
Still another object of this invention is to provide a device in which the magnetic fields are such that they not only focus the electrons from the electron source but also affect their orbits near the plasma volume so that they spend much more time in this volume and both effects can greatly increase the total inneraction and the amount of energy transferred to the plasma.